To energize a DC coil the Arduino is not the limitation. The switch and powersupply are typically the limitation. You should choose a MosFet that can deliver the current you want. DigiKey has an excellent webpage for selecting MosFets.

I'll guess, unless you are using a car battery, your powersupply is likely the limit

Question, will you be controlling the coil current using PWM?

If NO then I would drive the MosFet with an optoisolator (like a 4N25), this will keep the high current isolated from the Arduino, this will reduce your headaches in the long run as coils tend to generate voltage spikes that would otherwise be hard to suppress at the Arduino.

Please do not PM me with thread based messages. If your thoughts are worth responding, the group should benefit from your insight.

I AM BUILDING an induction launcher that can vary the strength and frequency of what is launched, a few times per second.

I am using two electromagnets, one to launch and the other to be launched. The strength needs vary from enough to be repelled to enough to lift 3lbs 1 foot high.

For the electromagnets I don't know the gauge of wire to be used or how many turns so don't know the area. I want to focus on how many Amps I can even get and will use that for finding out the wire gauge and turns.

FOR NOW I need to focus on the relay, mosfets? were suggested - and yes I do believe I need DC amps for the electromagnets.

Since Amps mean current and current is good I need to find out just how many amps I can work with the Arduino Uno and how to connect everything correctly.

I would appreciate some suggestions as for components.

The inductance of the coils, which you don't know, will severely limit how fast you can build up the current in the coils. The way everyone else does this is to charge very large capacitors to a high voltage and then discharge the capacitors through the coil. The high voltage forces the current while the inductance tries to limit it. It all comes down to time constants.

So if I use mosfets how would I connect them to the Arduino, wall outlet for power and to each electromagnet? Can I get an electrical diagram.

And how many amps do I even need to lift/launch 3lbs 25cm?

Is everyone afraid to tell the OP he is designing this thing completely backwards?

You need to compute the energy needed per second to begin to lift his 3lb weight and to move it some distance, against gravity, in some unknown time.

Once you have the energy required for your project, then you can compute the magnetic force needed to begin to move the object. Then realize as soon as it is a bit away from the electromagnet, the magnetic force is now reduced and more force will be needed to move another increment, and continue this process until 25 cm is reached.

Knowing the force required for each step, now you can compute the ampere turns required to generate this force. Knowing that, you can decide on the size of the wire that will handle the current and the insulation of the wires to withstand the heat generated.

Once that is all designed, you can begin to design the current supply for the coils.

Are you going to use some magnetic material for the wire turns to be wrapped around? If so, that will need to be considered in making the electromagnet.

As Paul_KD7HB said, I think your approach is orders of magnitude away from what you need.

The repeated reference to "wall warts" tells me you don't have a feeling for the amount of power you need.

I suggest you look through a catalog of DC solenoids and see the amount of power needed to create force under optimum physical conditions. Now consider that an electric field is reduced by the cube of the distance from the actual coils to the object you are attempting to move.

Now you said you wish to move 3 lbs 1 foot. Look at the solenoids for force and stroke length. You will find the typical stroke (i.e. movement) is far less than your desired 1 foot.

Next pickup up your wall wart (or any wall wart) look at the amps it is capable of........ compare it to the current the solenoids you might find......see if you are close.

John

Please do not PM me with thread based messages. If your thoughts are worth responding, the group should benefit from your insight.

When you are learning like this it is best to take thing is small sections.

I suggest you get some #14 AWG wire and make a coil. Ideally you would like "enameled" wire like one would use in a transformer but to start I would go to my local Home Depot or similar and purchase some #14 wire. How much wire to purchase? see below

Coil:

Do you know the shape of the coil? (i.e. tall and thin or all bunched together etc)Do you have an estimate of the diameter you need?

Once you get these then calculate the length and buy 25% more.

Wind your coil and connect it with a heavy switch or simply by hand. But be careful when you de-energize the coil the collapsing magnetic field will create a high voltage on the coil wires that will shock you if you are holding the copper part of the wires.

How will you know if you are getting close to your 1T goal?

There are several magnetic circuit calculators on the internet you might try one of them to get a starting point for the coil design.

Please do not PM me with thread based messages. If your thoughts are worth responding, the group should benefit from your insight.